Idle surging

[89K5guy]

When I am at idle especially in drive, the idle surges up and down.Any ideas on what to look for?

 

[mouse]

Start by looking for vacuum leaks. Replace any lines that look questionable, then use a small propane bottle to search for leaks. Do not light the propane, just turn it on and point it towards various items on/around the intake. If the idle increases/smoothes out, then you've found the leak. The propane will be drawn in at the leak and stop the leak from making the fuel/air ratio too lean.

 

[K5Greek]

Im having the same trouble with mine. Ive replaced the 02 sensor, wires, plugs, egr, new thermostat(put new rad. in) and Ive checked for leaks with no success. Not sure what to do here either

 

[MuddQueenK5]

Start by looking for vacuum leaks. Replace any lines that look questionable, then use a small propane bottle to search for leaks. Do not light the propane, just turn it on and point it towards various items on/around the intake. If the idle increases/smoothes out, then you've found the leak. The propane will be drawn in at the leak and stop the leak from making the fuel/air ratio too lean.

Another method you can spray carb/TB cleaner in "trouble areas" and it's the same principle, if the RPM's go up then you have a leak.

 

[NEK5]

Start by looking for vacuum leaks. Replace any lines that look questionable, then use a small propane bottle to search for leaks. Do not light the propane, just turn it on and point it towards various items on/around the intake. If the idle increases/smoothes out, then you've found the leak. The propane will be drawn in at the leak and stop the leak from making the fuel/air ratio too lean.

how can you check for vaccum leaks????

 

[MuddQueenK5]

how can you check for vaccum leaks????

I think he is saying to take propane (don't light it obviously) and just run it over the vac lines. If the idle goes normal then that area is the cause?

You may also be able to use soapy water. Just spray problem areas (where the vac lines connect or possible kinks) if you see bubbles, then you know where the leak is.

 

[NEK5]

thanks

 

[chevyk2500hd]

You can't use soapy water. It is called a vacuum leak for a reason. It will suck the water into the engine not blow bubbles. I don't recommend doing this. Carb cleaner or starting fluid are good choices.